System and method for regenerating a catalytic particulate filter located in a diesel engine exhaust line

ABSTRACT

A system for regenerating a catalytic particulate filter located in a diesel engine exhaust line, including an electronic control unit, a controlled fuel injector arranged upstream of the catalytic particulate filer and supplied with fuel by a controlled pump, and a sensor for measuring the fuel supply pressure of the injector. The system further detects a defect in the activating state of the pump based on the fuel supply pressure of the injector.

The present invention relates to a system and a method for regenerating a catalytic particulate filter located in the exhaust line of a diesel engine.

A catalytic particulate filter traps particles of soot emitted by the engine. To prevent the filter from becoming blocked, periodic regeneration phases burn off the trapped particles. The trapped particles are burnt off by increasing the temperature of the exhaust gases.

The French patent application filed under the number 04 53187 (Renault) relates to the regeneration of a catalytic particulate filter by injecting fuel into the exhaust. The fuel is injected by an injector located in the exhaust line of a diesel engine upstream of the catalytic particulate filter. A system such as this for regenerating a catalytic particulate filter presents new risks should it fail. However, that document does not disclose any system for monitoring the fuel pump that supplies fuel to the injector located in the exhaust line.

One object of the invention is to check that the state of activation of the fuel pump for supplying the injector in the vehicle exhaust line with fuel does actually correspond to the desired state of activation of the fuel pump.

Thus, in a first aspect, the invention proposes a system for regenerating a catalytic particulate filter located in the exhaust line of a diesel engine. The regeneration system comprises an electronic control unit, a controlled fuel injector located upstream of the catalytic particulate filter and supplied with fuel by a controlled pump, and a sensor for measuring the pressure at which fuel is supplied to said injector. The system further comprises detection means for detecting a fault with the state of activation of the pump on the basis of the pressure at which fuel is supplied to said injector.

In other words, the detection means detect a fault with the state of activation of the pump when the pump is active when it should be inactive or when the pump is inactive when it should be active. It is therefore possible to detect defective operation of such a catalytic particulate filter regeneration system and thus be able to avoid failure of such a system.

The invention makes it possible to improve the safety of the occupants of the vehicle by detecting a failure in the state of activation of the pump used to supply fuel to the injector positioned upstream of the catalytic particulate filter.

In a preferred embodiment, said detection means comprise first comparison means for comparing the pressure at which fuel is supplied to said injector against a first threshold pressure.

In an advantageous embodiment, said detection means comprise second comparison means for comparing the respective value of first system operating parameters against first predetermined values.

Conditions on system operating parameters need to be met in order for an inactivity fault with the pump to be able to be detected. In other words, conditions on system operating parameters have to be met in order to be able to detect that the pump is active when it should be inactive.

In a preferred embodiment, said detection means are designed to detect an inactivity fault with the pump when, for a period of time at least equal to a first predetermined period of time, the pressure at which fuel is supplied to said injector exceeds said first threshold pressure and said first parameters have adopted said respective first predetermined values.

For an inactivity fault with the pump to be detected and acknowledged it is necessary for the aforementioned conditions to be satisfied for a period of time at least equal to a first predetermined period of time.

In a preferred embodiment, said detection means comprise third comparison means for comparing the pressure at which fuel is supplied to said injector against a second threshold pressure.

In an advantageous embodiment, said detection means comprise fourth comparison means for comparing the respective value of second system operating parameters against second predetermined values.

Furthermore, said detection means are designed to detect an activity fault with the pump when, for a period of time at least equal to a second predetermined period of time, the pressure at which said injector is supplied with fuel is below said second threshold pressure, and said second parameters have adopted said respective second predetermined values.

In other words, in order to be able to detect an activity fault with the pump it is necessary for the pressure at which fuel is supplied to the injector to be below the second threshold pressure and for the system operating parameters to have adopted predetermined values for a period of time at least equal to a second predetermined period of time.

The first and second predetermined periods of time may, for example, be equal.

For example, said first parameters comprise information representing the state of the demand for activation of said pump, information representing the state of stabilization of the pressure at which fuel is supplied to said injector, information representing the state of operation of the sensor that measures the pressure at which fuel is supplied to said injector, information representing the state of operation of said pump, and information representing the state of operation of said injector.

A state of activation of the pump is to be understood to mean either a state in which the pump is active, or a state in which the pump is nonactive or inactive. The state of operation of an element of the system corresponds to an operation detected with or without a fault, for example with or without an electrical fault.

For example, said second parameters comprise information representing the state of the demand for activation of said pump, information representing the state of operation of the sensor that measures the pressure at which fuel is supplied to said injector, information representing the state of operation of said pump, and information representing the state of operation of said injector.

For example, said first predetermined values respectively represent the absence of a demand to activate the pump, a stabilized pressure, the absence of a fault with the operation of the sensor that measures the pressure at which fuel is supplied to said injector, the absence of a fault with the operation of said pump, and the absence of a fault with the operation of said injector.

For example, said second predetermined values respectively represent a demand to activate the pump, the absence of a fault with the operation of the sensor that measures the pressure at which fuel is supplied to said injector, the absence of a fault with the operation of said pump, and the absence of a fault with the operation of said injector.

In another aspect the invention proposes a method for regenerating a catalytic particulate filter located in the exhaust line of a diesel engine. A fault with the state of activation of a controlled pump is detected on the basis of the pressure at which fuel is supplied to a controlled fuel injector positioned upstream of the catalytic particulate filter and supplied with fuel by said pump.

Further objects, features and advantages of the invention will become apparent from reading the following description of a number of nonlimiting examples given with reference to the attached drawings in which:

FIG. 1 is a block diagram of one embodiment of a system according to one aspect of the invention;

FIG. 2 is a block diagram illustrating the pressure at which fuel is supplied to the pump as a function of the pump activation command for normal pump operation; and

FIG. 3 is a block diagram of one embodiment of the method according to one aspect of the invention.

FIG. 1 depicts a system according to the invention, carried on board a motor vehicle. The exhaust line 1 of a motor vehicle fitted with a diesel engine comprises a catalytic device 2 for oxidizing hydrocarbons and carbon monoxide.

The exhaust line also comprises a catalytic particulate filter 3 comprising an oxidation catalytic converter 4 and a particulate filter 5.

An injector 6 sprays fuel upstream of the oxidation catalytic converter 4. The oxidation catalytic converter 4 is periodically called upon, during the phases in which the particulate filter 5 is being regenerated, to create heat to regenerate the particulate filter 5. Injecting fuel via the injector 6 allows the temperature of the exhaust gases to be raised. The injector 6 is supplied with fuel by a line 7 connecting the injector 6 to a fuel tank 8. A fuel pump 9 supplies the injector 6 with pressurized fuel along the line 7.

The fuel supply line 7 is equipped with a sensor 10 for measuring the pressure P at which the injector 6 is supplied with fuel.

The injector 6, the sensor 10 and the pump 9 are connected to an electronic control unit 11 by connections 12, 13 and 14, respectively.

The electronic control unit 11 comprises a detection module 15 for detecting a fault with the state of activation of the pump 9 on the basis of the pressure P at which fuel is supplied to the injector 6 as measured by the pressure sensor 10.

The detection module 15 comprises a first comparison module 16 for comparing the pressure P at which fuel is supplied to the injector 6, as measured by the pressure sensor 10, against a first threshold pressure P_(thresh) _(—) _(min).

The first comparison module 16 makes it possible to test whether the pressure P at which fuel is being supplied to the injector 6 is above a first threshold pressure P_(thresh) _(—) _(min).

The detection module 15 further comprises a second comparison module 17 for comparing the respective value of first system operating parameters against first predetermined values. The first parameters comprise, for example, information representing the state of the demand for activation of the pump 9, information representing the state of stabilization of the pressure P at which fuel is supplied to the injector 6, information representing the state of operation of the sensor 9 that measures the pressure P at which fuel is supplied to the injector 6, information representing the state of operation of the pump 9, and information representing the state of operation of the injector 6.

The detection module 15 also comprises a third comparison module 18 for comparing the pressure P at which fuel is supplied to the injector 6 against a second threshold pressure P_(thresh) _(—) _(max).

Furthermore, the detection module 15 comprises a fourth comparison module 19 for comparing the respective value of second system operating parameters against second predetermined values.

FIG. 2 is a schematic diagram of the change in the pressure P at which fuel is supplied to the injector 6 as a function of activation and deactivation of the pump 9 supplying fuel to the injector 6. FIG. 2 illustrates activation or deactivation of the pump 9 with no fault with the state of activation of the pump 9.

At a moment t₁, activation of the pump 9 is commanded. Instantly, the pressure P at which fuel is supplied to the injector 6 switches from the value P₁ to the value P₂. The pressure P at which fuel is supplied to the injector 6 is measured by the sensor 10 that measures the fuel pressure P in the line 7. For example, the value P₁ is of the order of 3 bar, and the value P₂ is of the order of 5.5 bar.

The pressure P at which fuel is supplied to the injector 6 remains stable at the value P₂ until a moment t₂ when deactivation of the fuel pump 9 is commanded. The pressure P at which fuel is supplied to the injector 6 then decreases for a period of time Δt_(deac) until it reaches the value P₁.

FIG. 3 illustrates one embodiment of the method according to the invention. The pressure measuring sensor 10 continuously measures the pressure P at which the injector 6 is supplied, and transmits the measured values to the electronic control unit 11 via the connection 13, (step 20). At the same time, a fault of activation of the pump 9, and a fault of non-activation of the pump 9 are detected on the basis of the pressure P at which fuel is supplied to the injector 6.

The branch 21 corresponds to detection of a fault of non-activation of the pump 9 and the branch 22 corresponds to detection of a fault of activation of the pump.

In branch 21, the starting point is to test whether the pressure P at which fuel is supplied to the injector 6 exceeds the first threshold pressure P_(thresh) _(—) _(min) and whether the first system operating parameters have adopted the first predetermined values (step 23). This is because in order for there to be a fault of non-activation of the pump, that is to say in order for the pump to be active when it should be inactive, the pressure P at which fuel is supplied to the injector 6 has to exceed a first threshold pressure P_(thresh) _(—) _(min) slightly above the pressure P₁. The first system operating parameters have also to have adopted the first predetermined values. In other words, it is also necessary for the information representing the state of the demand to activate the pump 9 to represent the absence of a demand to activate the pump 9, for the information representing the state of stabilization of the pressure P at which fuel is supplied to the injector 6 to represent a stabilized pressure, for the information representing the state of operation of the sensor 10 that measures the pressure P at which fuel P is supplied to the injector 6 to represent the absence of an operating fault with the measurement sensor 10. It is also necessary for the information representing the state of operation of the pump 9 to represent the absence of a fault with the operation of the pump 9, and for the information representing the state of operation of the injector 6 to represent the absence of a fault with the operation of the injector 6.

If these conditions (step 23) are satisfied for at least a first predetermined period of time Δt₁ (step 24) then a fault of non-activation of the pump (step 25) is detected because the pump is active when it should not be.

In the branch 22, the starting point is to test whether the pressure P at which fuel is supplied to the injector 6 is below the second threshold pressure P_(thresh) _(—) _(max), and whether the second system operating parameters have adopted the second predetermined values (step 26). This is because in order for there to be a fault of activation of the pump, that is to say for the pump to be inactive when it should be active, the pressure P at which fuel is supplied to the injector 6 has to be below a second threshold pressure P_(thresh) _(—) _(max) slightly lower than the pressure P₂. The second system operating parameters have also to have adopted the second predetermined values. In other words, it is also necessary for the information representing the state of the demand to activate the pump 9 to represent a demand to activate the pump 9, for the information representing the state of operation of the sensor 10 that measures the pressure P at which fuel P is supplied to the injector 6 to represent the absence of a fault of the operation of the measurement sensor 10. It is also necessary for the information representing the state of operation of the pump 9 to represent the absence of a fault in the operation of the pump 9, and for the information representing the state of operation of the injector 6 to represent the absence of a fault with the operation of the injector 6.

If these conditions (step 26) are met for at least a second predetermined period of time Δt₂ (step 27) then a fault of activation of the pump (step 28) is detected because the pump is inactive when it should be active.

There is no need, in this case, to check that the pressure P at which fuel is supplied to the injector 6 is stabilized, because the period of deactivation Δt_(deac) of the pump 9 is detected by another test means and the system described is inactive when the pump 9 is in the deactivated phase. A deactivated phase corresponds to a period Δt_(deac), for example of the order of 30 minutes, during which the pressure drops from the value P₂ corresponding to the pump 9 being active to the value P₁ corresponding to the pump 9 being inactive.

The present invention makes it possible to check the state of activation of the pump that supplies fuel to an injector positioned upstream of a catalytic particulate filter and thus improve control over the operation of the filter regeneration phases. 

1-12. (canceled)
 13. A system for regenerating a catalytic particulate filter located in an exhaust line of a diesel engine, comprising: an electronic control unit; a controlled fuel injector located upstream of the catalytic particulate filter and supplied with fuel by a controlled pump; a sensor that measures pressure at which fuel is supplied to the injector; and detection means for detecting a fault with a state of activation of the pump based on the pressure at which fuel is supplied to the injector.
 14. The system as claimed in claim 13, in which the detection means comprises first comparison means for comparing the pressure at which fuel is supplied to the injector against a first threshold pressure.
 15. The system as claimed in claim 14, in which the detection means comprises second comparison means for comparing a respective value of first system operating parameters against first predetermined values.
 16. The system as claimed in claim 15, in which the detection means further detects an inactivity fault with the pump when, for a period of time at least equal to a first predetermined period of time, the pressure at which fuel is supplied to the injector exceeds the first threshold pressure and the first parameters have adopted the respective first predetermined values.
 17. The system as claimed in claim 15, in which the detection means comprises third comparison means for comparing the pressure at which fuel is supplied to the injector against a second threshold pressure.
 18. The system as claimed in claim 17, in which the detection means comprises fourth comparison means for comparing the respective value of second system operating parameters against second predetermined values.
 19. The system as claimed in claim 18, in which the detection means further detects an activity fault with the pump when, for a period of time at least equal to a second predetermined period of time, the pressure at which the injector is supplied with fuel is below the second threshold pressure, and the second parameters have adopted the respective second predetermined values.
 20. The system as claimed in claim 15, in which the first parameters comprise information representing a state of demand for activation of the pump, information representing a state of stabilization of the pressure at which fuel is supplied to the injector, information representing a state of operation of the sensor that measures the pressure at which fuel is supplied to the injector, information representing a state of operation of the pump, and information representing a state of operation of the injector.
 21. The system as claimed in claim 18, in which the second parameters comprise information representing a state of demand for activation of the pump, information representing a state of operation of the sensor that measures the pressure at which fuel is supplied to the injector, information representing a state of operation of the pump, and information representing a state of operation of the injector.
 22. The system as claimed in claim 15, in which the first predetermined values respectively represent absence of a demand to activate the pump, a stabilized pressure, absence of a fault with the operation of the sensor that measures the pressure at which fuel is supplied to the injector, absence of a fault with the operation of the pump, and absence of a fault with the operation of the injector.
 23. The system as claimed in claim 18, in which the second predetermined values respectively represent a demand to activate the pump, absence of a fault with the operation of the sensor that measures the pressure at which fuel is supplied to the injector, absence of a fault with the operation of the pump, and absence of a fault with the operation of the injector.
 24. A method for regenerating a catalytic particulate filter located in an exhaust line of a diesel engine, comprising: detecting a fault with a state of activation of a controlled pump based on pressure at which fuel is supplied to a controlled fuel injector positioned upstream of the catalytic particulate filter and supplied with fuel by the pump. 